Screw driver



Jan. 1, '1924 1,479,506

H. F. KELLEMEN S CREW DRI VER Filed Jan. 7, 1922 Patented Jan. 1, 1924.

stares are Wa n ri e.

WELLS COMPANY, OF DULUTH, MINNESOTA, A CORPORATION OF NEVI JERSEY.

SCREW DRIVER.

Application filed January To all whom it may concern Be it known that I, HENRY FRANCIS IIELLEMEN, a citizen of the United States, residing at Duluth, county of St. Louis, State of Minnesota, have invented certain new and useful Improvements in Screw Drivers, of which the following is a spec1fi cation.

The object of my invention is to provide a screw driver so constructed that the drive or application of power will be posltively transmitted from the handle to the shank and blade without any possibility of the shank turning in the handle and becoming inoperative.

A further object is to provide a screw driver having a blade, so formed that there will be no tendency to become disengaged from the screw slot when a twisting motion is applied to the tool.

Other objects of the invention will appear from the following detailed description.

The invention consists generally in various constructions and combinations, all as hereinafter described and particularly pointed out in the claims.

In the accompanying drawings forming part of this specification,

Figure 1 is a view, partially in section, of a screw driver embodying my invention,

Figure 2 is a view showing the ferrule pushed out on the shank of the tool, away from its seat on the handle,

Figure 3 is a sectional view on the line 33 of Figure 1,

Figure lis an end view of the ferrule,

Figure 5 is a diagrammatic view, showing how the curve of the blade is made on a radius to make it slightly thinner in the rear of the tip than it is at the extremity,

Figure 6 is a detail view, illustrating the end of the blade fitting into the slot in the screw head.

In the drawing, 2 represents the shank of the tool and 3 the blade having the usual end to fit the slot 4: in the screw head 5. lVhere these ends are wedge-shaped and decrease gradually in thickness to the end of the blade, there is a tendency to turn or swing out of the slot when a twisting motion is applied to the driver, due to the engagement of the faces of the blade with the upper edge of the slot in the screw head.

To eliminate this difficulty, I make the opposite faces of the blade concave, as indi- 7, 1922. Serial No. 527,720.

Figure 6, will fit into and bear against the corners of the slot in the screw head and the twisting motion of the tool will be transmitted through these corners directly to the crew head, while the concave portion of the blade will be spaced from the walls of the slot and will not normally come in contact therewith and consequently there will be no tendency for the blade of the tool to tilt or turn out of the slot. While I have shown and described the means to prevent the end of the screw driver shank from twisting out of the screw-head, I make no claim to the same in this application.

In forming the shank, I provide an integral body 7 thereon rectangular in form, with one end seated against the handle 8 when the parts are assembled, and with the end of the shank 9 projecting into a socket 10 in the handle. The end of the handle has faces 11 formed thereon and inclined slightly toward the end to merge into and form continuations of the corresponding faces of the block 7, so that when the shank is inserted into the handle of the tool, the block and the faces of the handle will as sume a frusto-conical form.

To unite the surfaces of the body 7 and the end of the handle, I provide a tapered ferrule 12 having a socket therein to receive the body 7 and the end of the handle so that when the parts are wedged together, the rectangular surfaces of the ferrule fit snugly against the corresponding surfaces of the shank and handle, and there will be no possibility of the handle twisting on the shank or the shank turning in the handle, but the motion or power applied to the handle will be positively transmitted through the shank to the head of the screw.

I have shown the block on the shank of the screw driver provided with four faces and a corresponding number on the end of the handle, and the interior surface of the ferrule, but it will be understood that I do not confine myself to this construction, for in various ways it may be modified and still be within the scope of my invention, as, for

instance, the number of bearing surfaces may be increased or diminished, or the shape of these surfaces modified and still adapt the device forpositively transmitting power from the handle to the shank.

I claim as my invention 1. A tool comprising a shank, having a block thereon forming a shoulder surrounding the shank, said block being rectangular in cross-section, and having tapered external bearing surfaces, said shank extending beyond said block, and ahandle having a socket to receive said shank, the end of said handle engaging said block and limiting the movement of said shank into said socket, the end of said handle being rectangular in cross-section and having tapered bearing surfaces forming continuations of the surfaces of said block, and a tapered ferrule having internal faces to it the surfaces of said block and hearing.

2. A screw driver comprising a shank, a handle having asocket to receive one end of said shank, said shank having tapered bearing surfaces intermediate to its ends, and said handle having similar surfaces flush with those of said shank, and a: ferrule engaging the tapered surfaces of said shank and handle and bridging" the joint between them and formed to lock said shank and handle against relative turning movement.

In Witness whereof, I have hereunto set my hand thisBrd da of Jan, 1922.

HENRY FRANCIS KELLEMEN. 

